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Matthew J. R. Simpson, J. Even Ø. Nilsen, Oda R. Ravndal, Kristian Breili, Hilde Sande, Halfdan P. Kierulf, Holger Steffen, Eystein Jansen, Mark Carson,

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Presentasjon om: "Matthew J. R. Simpson, J. Even Ø. Nilsen, Oda R. Ravndal, Kristian Breili, Hilde Sande, Halfdan P. Kierulf, Holger Steffen, Eystein Jansen, Mark Carson,"— Utskrift av presentasjonen:

1 Matthew J. R. Simpson, J. Even Ø. Nilsen, Oda R. Ravndal, Kristian Breili, Hilde Sande, Halfdan P. Kierulf, Holger Steffen, Eystein Jansen, Mark Carson, Olav Vestøl. Norsk klimaservicesenter rapport nr. 1/2015. Jan Even Øie Nilsen, Nansen senter for miljø og fjernmåling, Sea Level Change for Norway Past and Present Observations and Projections to 2100

2 Foredraget i dag 1.Rask oversikt over prosjektet og hovedresultatene 2.Mer detaljert om rapportens deler

3 Motivasjon Norge har store verdier langs kysten Kjennskap til framtidige hav- og stormflonivåer er avgjørende for kystsoneforvaltning. Naturlig tidspunkt for oppdatert rapport – Økt kunnskap og bedre klimamodeller (IPCC AR5) – Oppdaterte tall for landheving – Oppdatert stormflostatistikk Samarbeid mellom Kartverket og Nansensenteret/Bjerknessenteret Initiert av Miljødirektoratet Et bidrag fra Norsk klimaservicesenter Faglig grunnlag om havnivå – til forvaltningen – til Klima i Norge 2100

4 4 Ved høye utslipp Varmere klima  Smelting av is på land Varmeutvidelse av havet Varmere klima  Smelting av is på land Varmeutvidelse av havet Årsaker til havnivåstigning

5 Mer enn år siden: Fortsatt: 5 Ved høye utslipp m/100 år Havnivåendring Landheving er viktig i Norge Landheving mm/år

6 Framskrivinger av havnivå i Norge Ved høye utslipp m/100 år Havnivåendring Stavanger meter Oslo meter

7 7 Tidevann 200 års 1 års 200 års 20 års 1000 års Kaikanten på Bryggen Hyppighet cm havnivåstigning Væreffekter Stormflonivåer høyere Oversvømmelser oftere Stormflonivåer høyere Oversvømmelser oftere I dag:Innen 2100: KARTNULL Konsekvenser av havnivåstigning Kartverket.no/sehavniva

8 8 200-års stormflonivå kan overstiges i … … år i dette århundret. 20-års stormflonivå kan overstiges i … … år i dette århundret. Havnivåendring til 2081–2100 (cm) Oslo Stavanger Bergen Trøndelags- Tromsø Honningsvåg kysten Landsoversikt havnivåendring og stormflo

9 Rapporten mer i detalj 1.Introduction Motivation, processes, paleo perspectives, observed global sea level 2.Background and Previous Work on Future Projections IPCC AR5, our previous reports 3.Observed Sea Level Changes in Norway Paleo observations, tide gauge records, comparison with altimetry, contributions 4.Present-day Vertical Land Motion in Norway GIA-modeling, GPS, leveling, IPCC AR5 5.Projected 21 st Century Sea Level Changes for Norway CMIP5, contributions, SAL, rates, uncertainties/variability, beyond AR5 ranges 6.Extreme Sea Levels along the Coast of Norway Storm surges, no change, tidal regime, extreme value analysis, ACER, return periods 7.Combining Storm Surge Statistics with Sea Level Projections Hunter’s method, Hunter modified for ACER, allowances, future return heights

10 1. Introduction Observed contributions to global SLR

11 2. Background and Previous Work on Future Projections IPCC AR5 represents a fundamental step forward Regional sea level projections are now provided by the IPCC for the first time Norwegian Mapping Authority and Nansen/Bjerknessenteret has previously published separate reports Likely range across scenarios 0.26–0.82 m over the period 1986–2005 to 2081–2100 Emission Scenarios Sea level change RCP2.6 RCP8.5 RCP4.5

12 Relative Sea Level Sea surface height (SSH) – SSH is relative to the reference ellipsoid – Satellites measure SSH Relative sea level (RSL) – RSL is relative to the solid Earth surface – Tide gauges measure RSL A change in RSL is the difference between the change in SSH and the vertical land motion (VLM).

13 3. Observed Sea Level Changes in Norway Relative sea level rates at the Norwegian tide gauge network reflect the pattern of land uplift. South-, west-, and northern Norway is now experiencing sea level rise in spite of land uplift (red arrows). After correcting for land uplift, the coastal average SSH rate of change is 1.9 mm/yr for 1960–2010 and 3.6 mm/yr for 1993–2014. Altimetry based rates concur with corrected tide gauge rates (1993–2014). Observations point to warming ocean and melting land ice as the main contributors to the trends.

14 4. Present-day Vertical Land Motion in Norway Glacial isostatic adjustment (GIA) dominates vertical land motion in Norway. New GPS data with better spatial coverage than before. Numerous levelling observations. We collocate GPS and levelling. Tested better against the longest GPS series. We have more confidence in our solution, the values and uncertainties being essentially based upon the GPS and levelling observations. Similar to that used in AR5, but smaller uncertainties. Gravitational effects of GIA on sea level are taken into account (0.2–0.5 mm/yr). GIA-model Levelling GPS GPS & levelling

15 5. Projected 21 st Century Sea Level Changes for Norway Regional projections from AR5/CMIP5. Plus estimated self attraction and loading (SAL). Replace VLM with our own estimates. Interpolated to the 276 coastal municipalities. Projections for emission scenarios RCP2.6, RCP4.5, and RCP8.5. Sea level change from 1986–2005 to 2041–2060, 2081–2100, and We use the AR5 likely range, 5 to 95% uncertainty bounds. RCP8.5 m/100 yr ∆RSL

16 5. Projected 21 st Century Sea Level Changes for Norway VLM Steric/dyn AntarcticaGlaciers Greenland Contributions:

17 Stavanger meter Oslo meter RCP8.5 m/100 yr ∆RSL 5. Projected 21 st Century Sea Level Changes for Norway Contributions RCP4.5

18 6. Extreme Sea Levels along the Coast of Norway Knowledge of future extreme water levels is important for coastal management. There are no observations or projections of wind and wave climate that can suggest storm surge activity will change significantly in the future. We obtain current return heights by statistical analysis of the 22 tide gauge records along the Norwegian coast (squares). We use the ACER method since it allows for use of more data and is less sensitive to outliers and missing data. The 20, 200 and 1000-year return heights as well as confidence intervals are calculated. 200 year – HAT200 yearHAT

19 7. Combining Storm Surge Statistics with Sea Level Projections 200 year RCP8.5 m/100 yr ∆RSL

20 20 Tidevann 1 års 200 års 20 års 1000 års Kaikanten på Bryggen Hyppighet cm havnivåstigning Væreffekter I dag:Innen 2100: KARTNULL Kartverket.no/sehavniva 7. Combining Storm Surge Statistics with Sea Level Projections 1.Sannsynlighet for ekstremhendelser 2.Sannsynlighet for havnivåendringer Modell- middel 95% 5%

21 7. Combining Storm Surge Statistics with Sea Level Projections Allowances give the height an asset needs to be raised so the probability of storm surge flooding remains the same under a given sea level change. We adapt the framework of Hunter for calculating allowances, to the ACER method. In this example we make the assumption that our regional sea level projections are normally distributed. AR5 assess 66–100% probability on the model range. Thus the model range can correspond to 17 to 83% or 5 to 95% probability bounds. Allowances by Hunter’s method with ACER is very sensitive to this choice. We emphasize that other, and maybe skewed, distributions may be more appropriate. 95% 5% 83% 17% 72 cm104 cm

22 Changes in Return Heights StavangerOslo Large difference between return heights Small sea level rise => Small change in flooding frequency Small difference between return heights Large sea level rise => Large change in flooding frequency

23 års stormflonivå kan overstiges i … … år i dette århundret. 20-års stormflonivå kan overstiges i … … år i dette århundret. Havnivåendring til 2081–2100 (cm) Oslo Stavanger Bergen Trøndelags- Tromsø Honningsvåg kysten Landsoversikt havnivåendring og stormflo

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